Shooting for fancier fireworks: New displays are taking shape Engineers working to perfect designs and letters in the sky

July 04, 1996|By Ivan Amato | Ivan Amato,CONTRIBUTING WRITER

It is July 4, 1999. The Baltimore citizenry has crowded into the Inner Harbor, necks craned. The sound and trail of the first salvo of shells cranks up the excitement. Then all eyes track something that firework designers have been working toward for years. Spelled across the sky in letters of explosive color and light: "Baltimore 1999."

Tonight this scenario won't play out in Baltimore, or elsewhere, but the Inner Harbor show will contain the seeds of such future displays.

Shells that paint the sky with geometric shapes such as hearts, five-pointed stars, bow-ties and even peace signs represent today's cutting edge, says John Conkling, an adjunct chemistry professor at Washington College in Chestertown, and executive director of the American Pyrotechnics Association.

The show to be presented in Baltimore is expected to feature shapes from the giant fireworks company, Zambelli Internationale of New Castle, Pa., including a heart, a star and an hourglass.

The market for shapes is rising, according to Bob Kellner, who runs a fireworks wholesaling business north of Pittsburgh. "People are wanting fancier fireworks. They love the red hearts and purple hearts."

Conkling, a graduate of the Johns Hopkins University, says that "what might be lurking down the road are a series of fireworks that ignite simultaneously and spell out a message."

Who will be the first suitor to propose marriage with firework words?

Before such explosive and public proclamations become possible, however, engineers will have to tackle a few not-so-small limitations of the present generation of "pattern shells," as they are called.

The display that unfolds from "pattern shells" begins as a two-dimensional arrangement of sugar-cube-sized firework pellets pasted onto a paper sheet. The loaded paper is placed within a shell along with precisely positioned explosive powder. Once the lifting charge at the bottom of the shell propels it to an appropriate height, bursting charges hurl the pellets outward to create a brilliant, swelling version of the pattern in the sky.

This is tricky enough for successfully lighting the sky with hearts and stars. Any small errors and asymmetries in the packing will magnify as the firework expands. Charges that are misplaced, too powerful or too weak will skew the pattern.

"The current pattern shells are orientation dependent," Conkling says, meaning that the shape a spectator perceives depends on whether the shell explodes while right side up, upside-down, sideways or obliquely. So even when everything works as planned, not all of the pattern shells that go up appear as intended.

There are plenty of topsy-turvy hearts or peace signs, Conkling says.

The problem is especially vexing when it comes to firework letters. A shell that is supposed to spell "MOM" becomes "WOW" if it explodes upside down. At even stranger angles the firework letters would appear as less intelligible markings.

One of the handful of companies aiming to advance the art is Starr Display Fireworks in Fargo, N.D. "They pioneered much of this technology," Conkling says.

U.S. troops returning from the Persian Gulf war came home to aerial yellow bow-ties made by Starr, which also sells maple leaf patterns for Canadians. The company's catalog includes strawberries, shamrocks, triangles and squares.

Judging from the animation in the voice of Cameron Starr, founder and president, his pride and joy is the pyrotechnic elephant that grows to a whopping 350 feet long by 300 feet high.

Starr, who first started selling fireworks from a roadside stand in 1947, says his company is on the trail of firework writing. It has shipped a small number of first-generation letters, but he acknowledges the technology has a long way to go before readable words or sentences hit the skies.

"We are still working on ways of getting the letters to orient in the right way," he concedes. But Starr notes that none of the other two or three competitors has succeeded either.

Many factors, including wind speed, humidity and air pressure, conspire to ruin orientations. To tackle that, he says, people have experimented with tying ropes to the sides of shells or fiddling with the distribution of weight inside. "We have tried all of those over the years," he says. "To really perfect that [before we do], some company or investor will have to make a sizable investment in R&D."

Besides taking the pattern shell technology into more literate realms, firework designers have been using more whistle and crackle effects in place of the chest-thumping explosions that invariably raise the ire of some residents. "More cities, when they order displays, want more color and less noise," Conkling says.

The standard booms, known as "salutes," typically are made by a 2-ounce dollop of explosive in a cardboard cylinder.

The bright flash that accompanies each boom often is enhanced by the addition of aluminum powder.

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